It's all about what you put down when you fill out a form, and you may want to think twice when you are giving your private information to a public agency.

On Election Day, you vote in private. Your ballot is secret, but what is not so secret is your name, address and probably your home phone number. They are posted right on the wall at the polling place for everybody to see.

"They had my unlisted phone number and they had my husband's cell number and I was quite appalled when I saw that," said Aleta Mason from Oakland.

Mason was shocked to find her personal information publicly posted on Election Day.

"This is not good because anyone coming up here can see my phone number, can see anyone's phone number they can use it for the wrong reasons," said Mason. "Might as well put it up on a billboard, that's the way I feel."

"It's a legal requirement that we post what's called a street index outside of each polling place," said Alameda County Registrar Dave Macdonald.

Macdonald is talking about a state law which requires each polling place to post a list of all voters in the precinct.

Once you vote, your name is crossed off.

"It originally goes back to the idea that campaigns and politicians would like to know who in the neighborhood has voted, and who hasn't, that way they can use it to get out the vote," said Macdonald.

The list has your name, address and party affiliation. Most counties also list your home phone number -- some do not. In any case, your number will only appear if you put it down when you registered to vote.

But guess what? You don't have to give your phone number or an email address either.

"Once you create this kind of public record that includes your phone number and your email address, it becomes very difficult to put the genie back in the bottle," said Joe Ridout from Consumer Action.

Ridout warns against putting private information on a public record.

"It could be shared with other groups who could share it with others and before you know it you could be getting a lot of unwanted calls and unwanted spam," said Ridout.

Once you register to vote, certain groups can obtain your voter information, like where you live and when you voted. Anyone using it for academics, government, journalism or politics and private companies can sell your voter records if it's for political campaigns.

When we told Macdonald Aleta didn't want her number on the wall, he agreed to do something about it.

"I'm always very, very concerned about people's privacy," said Macdonald. "We're going to look and investigate how we can suppress that telephone field. And I think we can."

Meantime, Aleta found a clever way to hide her number. She re-registered to vote and this time, she left the phone number blank.

"I just really feel like, your privacy should be respected," said Mason.

Some registrars interpret the law to mean that they must post your phone number if you put it on your voter form. Others disagree.